Hydrocarbon conversion



Oct. 31, 11944. B. L EVEING ETAL HYDROCARBON CONVERSION Filed Jun 27, 1940 Patented Oct.` 31, 1944 nynaocAnBoN ojoNvERsIoN Bernard L. Evering and Edmond L. dOuville,

Chicago, Ill.,` assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana r Application June 27, 1940, Serial No. 342,652 s claims. 4(c1. 260g-683.4)

This invention relates to the conversion of hydrocarbons to improved motor fuels and relatesv more particularly to the conversion of normally liquid saturated hydrocarbons and mixtures thereof containing a preponderance of straightchain paraflins into products consisting predominantly of branched-chain parainic hydrocarbons.

There are usually available in modern petroleum refineries or in the production elds large quantities of straight-run naphthas, natural gasolines and distillates which contain considerable amounts of straight-chain paranic hydrocarbons. ASuch naphthas and gasolines have low octane numbers and therefore are not considered desirable for use as a motor fuel either as such or as a blend with other hydrocarbons. Substantially all such naphthas and natural gasolines, however, do contain minor amounts of branched-chain hydrocarbons which are potentially suitable for use as high anti-knock motor fuels but which are so diluted with straightchain paraflinic hydrocarbons that their effectiveness is usually almost completely masked for practical purposes.

It is an object of our invention to provide a process. for the conversion of normally liquid saturated hydrocarbons containing substantial amounts of straight-chain paraiiinic hydrocarbons to saturated branched-chain hydrocarbons of high octane number suitable for premium fuels.

Another object of our invention is to provide a process whereby naphthas and natural gasolines ofv low octane number are convertedinto hydrocarbon fuels having branched-chain paralnic hydrocarbons of suitable octane number and volatility for use as premium motorfuels.

A further object of our invention is to provide a, method for the production of valuable branched-chain paraiiinic hydrocarbons of Agasoline boiling range from low anti-knock naphtha containing a substantial amount of straightchain parainic hydrocarbons.

A still further object of our invention is to provide an improved process whereby normal paraliins.. can be more completely isomerized to branched-chain isomers in high yields.

Yet another object of our invention is to produce a substantially paraflnic aviationjfuel of suitable vapor pressure and boiling range from straight-run naphthas and natural gasolines.

Still another Object of our invention is to accelerate the rate of isomerization by removing lll at least a portion of the branched-chain paraffins from the feed by alkylation followed by 'fractionation, thus concentrating the normal paratfins in the feed to the isomerizer.

Another object of our invention is to convert light vnormally liquid paraiiinic naphthas into high octane paraflinic aviation safety fuels.

Other objects and advantages of our invention will become apparent from the following description read in conjunction with the drawing which forms a part of the specification. y

The single figure illustrates schematically' a form of apparatus suitable for carrying out one preferred embodiment of our invention.

Our process, in brief, contemplates the conversion of normally liquid branched-chain hydrocarbons in a substantially saturated paraffinic naphtha to branched-chain paramnic hydrocarbons of higher molecular weight by alkylation, their separation by fractionation, andthe conversion of the unalkylated straight-chain parains to the corresponding isoparaiiinic hydrocarbons byv isomerization and blending the combined products to yield a motor fuel of increased anti-knock value and improved distribution of hydrocarbons. Isomerization of normal parafns is never complete even under the most favorable practical conditions, an equilibrium between the isomeric and normal par'ans occurring atsome stage of the process. 'In the case of normal pentane this equilibrium at 330 F. is about 8.0% isopentane to 20% normal pentane. In the case of normal hexane the situation is more complex but we have found that an appreciable amount of normal hexane exists even in the most highly is'omerized mixtures. Hence, in order to convert higher percentages of the normal paraflins to the more valuable isomers it is necessary to bring about a separation of the normal and branched-chain hydrocarbons so that the`equilibrium can be disturbed, This can be eflected by fractionation in certain simple cases but in the more usual highly complex cases where there is serious overlapping of the boiling ranges of the vnormal and branched-chain isomers, fractionation alone is not practical. In our improved process this isv accomplished by elevating the boiling range of a substantial part of the--branched-chai'n isomers by alkylation and subsequently separating by fractionation the r'esulting higher-boiling alkylated isomers, thus straight-chain paraflinic hydrocarbons. ample, straight-run gasolines from` paranic andsubstantially free ofV olens.

Isimilar production areas.

be set up in isomerizing normal pentane to isopentane, or normal hexane to isohexane, and fractionation of alkylate from unconverted lowboiling normal paraflinic' hydrocarbons would therefore be unnecessary. However, if it is de,- sired to convert as much as possible of the low-4 boiling normal paraiiinic hydrocarbons to the isomeric form, or if it is desired to avoid degradation of the higher-boiling alkylate to less valuable vproducts of lower octane-number or fewer carbon atoms per molecule, the alkylate should be separated from the low-boiling constituents. Under the conditions of operation in the presence of aluminum chloride there will be conversion of the valuable higher-boiling alkylate to hydrocarbons of lower molecular weight, and/or conversion of the high antiknock hydrocarbons to hydrocarbons of lower knock rating. Since we desire to obtain the highest yield possible of the most valuable hydrocarbons suitable for aviation fuel, and since the production of isomeric low-boiling hydrocarbons at the expense .of higher-boiling high octane number hydrocarbons is not compatible with our process for producing a balanced aviation or motor fuel of high octane number, the fractionation of the alkylate from low-boiling normal parafllnic hydrocarbons is an essential part of our process. l

As has been suggested the feed stock to our process can be any substantially saturated normally liquid hydrocarbon fraction rich in For exor mixed base crude oil, such as thoseyfrom Mid- Continent, Michigan and-Pennsylvania oil fields, areusually high in straight-chain hydrocarbons Natural gasoline/fractions are also eminently suitable for our purposeand may be found in considerable quantities in the vicinity` of natural gaswells and So-called vdistillates from high pressure wells are also suitable.

" It is preferable that our feed stock be free or substantially free of aromatic and oleflnic I3 or mixed with the feed stock in line' I0 by' opening valve I c line I5. The oleiinic hydro- Y olenic stream in which the major portion of I carbons are preferably normally gaseous hydrocarbons of from two to four carbon atoms per molecule. It is generally desirable to use an the oleilns is ethylene, and special narrow cuts high in ethylene are very suitable. However,

hydrocarbons since such hydrocarbons greatly 4 impair or reduce the activity of the catalyst and decrease appreciably the amount of product obtainable per unit of catalyst. Generally speaking, we prefer feed stocks which contain less` "than V5% and especially those containing less than 0.5% to 1% of aromatic hydrocarbons, and having very little or no oleflnic hydrocarbons. This, therefore, eliminates to a large ex- 'tent cracked naphthas or other mixtures of un'- saturated `hydrocarbons available from petroleum refining. Cycloparaillnic or naphthenic hydrocarbons are not seriously objectionable. A substantially aromatic-free feed stock can be obtained foreur process either byI fractionation of a straight-run naphtha into a cut boiling below the boilingpoint of the simplest aromatics, for example, below.150. F., or by the solvent extraction of a straight-run'naphtha of wider boiling range with a selective solvent. A suitable naphtha for our purpose is one having a boiling range -of from aboutx30 F. .to about 158 Rand desirablyA not above 152 F. On the other hand. some natural gasollnes of higher boiling range having less than 5% aromatics and especially those containing less than 0.5% to 1% of aromatic hydrocarbons can'be used in their-entirety 'after stabilization. We. particularly prefer a mixture of hydrocarbons having present a y substantial amount of hydrocarbons having 5 and 6 carbon atoms Der molecule.

thane and methane can be tolerated and hydrogeny may be even beneficial as hereinafter described. Y Y

The alkylation product of ethylene with the `isoparaiiinic hydrocarbons of the feed stock produces isoparafnic hydrocarbons within the gasoline boiling range, Awhile with the use of the higher-boiling gaseous olens, hydrocarbons higher boiling than 'are usually found in gasoline may be obtained. In the event, therefore, that it is desirable to produce an aviation safety fuel characterized bythe presence of hydrocarbons of more than eight carbon atoms per molecule, the presence of propylene and butylene becomes advisable. A mixture of any two or more of these olefins, diluted if necessary by the cor `eslponding paraiiinic hydrocarbons, is a suit'- 4able oleflnc feed stock.

As catalysts for our process, we can employ an aluminum halide such as, for example, aluminumv chloride or aluminum bromide or an aluminum halide-hydrocarbon complex formed by the reaction of anhydrous aluminum halide with paraflinic hydrocarbons in the presence of a promoter such as hydrogen halide, for example, hydrogen chloride or hydrogen bromide. A suit able catalyst for our purpose isthe hydrocarbon complex formed during the isomerization of aromatic-free straight-run naphthas.

Generally speaking, sulfuric acid is not desir able for our process, since under ordinary condi-V tions it .does not promote the alkylation of isoparaflinic hydrocarbons with ethylene. However,

in those cases where no ethylene is present and only propylene and the butylenes are available for alkylation, sulfuric acid can beV employed asJ the catalyst. Sulfuric -acid can 'also be used if al promoter, such as silver sulfate or mercury' sulfate, is added, which permits the utilizationl of y l rectly to yalkylation reactor II by opening valve A I1 or can be mixed with the incoming feed stock fand olens by opening valve Illin-line` I9 which joinsline I0. Generally speaking, it is preferable to add the catalyst directly to the reactor rather than with the feed streams. l The catalyst concentration in alkylation reactor II may be from about 15 to about.90% by weight, preferably about 60% by weight of the feed contained in the reactor and may be not only aluminum chloride or an aluminum chlo4 ride-hydrocarbon complex, but may be a mixture of these two containing from 10to 90% aluminum .chloride andfrom 10 to 90% of the hydrocarbon complex.

Alkylation reactor II is maintained at a temperature of from about 30 F. to about 250 F..

perature can be controlled by a jacket about aikylation reactor through which a heating or cooling medium flows from line 2| and discharges through line 22. Intimate contact between the The pressure in alkylation reactor Il can be the vapor pressure of the reactants and the products at the operating temperature, or we can employ a hydrogen partial pressure of from about 50 to' about 1000, pounds per square inch, preferably about 200 to about 800 pounds per square inch. Hydrogen, therefore, can be added by line 24 and valve 25. The olefins should be added to the reactor in an amount such that the ratio of isoparafilnic hydrocarbons to the olens is at least 1:1 and preferably considerably higher, for ex'. ample, 3:1 to 4:1. The ratio of isoparailinic hydrocarbons to olenic hydrocarbons can be increased by limiting the amount of olens fed to the reactor or by recycling .isoparainic hydrocarbons after fractionation of the alkylate.

The alkylate plus unreacted olens, unconverted paralnic hydrocarbons, andhydrogen, if

'anced' fuel. convert these straight-chain paraiinic .hydro-1 hexanes, and/or heptanes have been vconverted to branched-chain heptanes, octanes and nonanes, respectively.` lThe alkylated hydrocarbons are of a highly branched-configuration, and ac` cordingly of high octane number, while possessing a boiling range within 'the limits desirable for premium fuels, although deficient in the more volatile constituents.

The unconverted straight-chain paralnic hy- .'irocarbons, on the other hand, are extremely low' in octane number, although of suitable volatility for blending with the alkylate to form a balvIt therefore becomes desirable to carbons to branched-chain hydrocarbons having the same number o f carbon atoms per molecule and, accordingly, they are directed from line 5| lthrough line 52 and valve 53 to isomerization -leading to reactor il.

reactor 54. In the event that considerable quantities of isoparanic hydrocarbons remain in the feed, these can advantageously be recycled from line 5| through line 55 and valve 55a to line Il) By adjusting valves 53 and 55a, itis possible to recycle a portion of the ilsop-arafiinic hydrocarbons to reactor il and direct the remainder to isomerization reactor 54,

"but generally speaking we 'prefer to'direct all of present, together with'the catalyst are withdrawn from alkylation reactor 'through line 26 and directed to separator 21 wherein a separation is made between the catalyst and the hydrocarbons. The catalyst is withdrawn through line 28 and can be recycled to the operation by opening valve 29 in line 36 which joins line I6. In the event y the catalyst is spent as vregards alkylation it can be withdrawn through lline 3| by opening valve 32' and discarded or regenerated as desired. Spent catalyst may also be useable in an isomerization reaction, to be described later, and can be directed thereto by opening valve- 33 in line 34.

In the event that hydrogen was employed in the alkylation reaction the pressure can be reduced and the hydrogen taken overhead from'separator 21 through line 35 and returned for furthe fraction in line 5| to` isomerizer 54. The alkylated hydrocarbons together with any higherboiling straight-chain hydrocarbons, such as for example, heptane and octane, are withdrawn through line ,56 and may be sent to storage ther use through valved line 36 which joins line 24 or discarded through valved line 31. The alkylate plus the unreacted olens and unconverted parainic hydrocarbons is withdrawn from separator 21 through line 38 and directed to fractionator 39. In the event that hydrogen was not released in separator 21 it can be taken overhead from fractionator 39- through line 40 and discarded by opening valve 4| 'in line 42. It can also `ing' valve 43 in line 44 and valve 45 in line 46 .whichjoinsline 24. Any olefins which were not completely reacted in alkylation reactor can 'be taken overhead through line 40 and recycled to the reactor through line 44, and `valve 41 in line 48-which joins line I2. Top-cooling means 49 and bottom-heating means 50 assist in the fractionation of the hydrocarbons in fractionator 39. Any methane and ethane present with the 'hydrogen in line 40 can be removed (by means be recycled to the alkylation reactor by open-l` through line 51 and valve 58 but preferably are directed to blending tank 59 through line 60 and valve 6| for blending with lower boiling isoparafiinic hydrocarbons preferably obtained from the isomerization reaction (to be described in more detail later) In the event that there were present in thev feed stock branched-chain hydrocarbons having y more Athan seven carbon atoms per molecule,

these may have been alkylated and therefore are desirably separated froml the alkylate boiling Within the gasoline range. ,'I'hese higher alkylates are very suitable for safety aviation fuels because of their high octane number and avoid re hazard because of their high flash point. The higher alkylates are withdrawn from fractionator 39 through line 62 and can be sent to storage through line 63 by opening valve 64. On the other hand, it may be desirable to include the higher boiling alkylates with those boiling ordinarily in the gasolinerange in which case the higher-boiling alkylate can be directed to line 56 by opening valve 65 in line 66 which joins line 56. Alternately, the entire alkylate can be withdrawn through line 62 and directe'dto blending tank 59. Any heavy polymers or tarryr matter which might have been formed are withdrawn from fractionator 39 through valved line 61.

Referring now to the isomerization-reaction, the predominantly straight-chain parafnic hydrocarbonsin line 52 are mixed with a hydrogen halide from line 6,8 and catalyst from line .69

and directed to isomerization reactor 54. As catalysts we can employ an aluminum halide, which e can be aluminum chloride or aluminum bromide in anhydrous form, or can .be the complex formed by the reaction of. an aluminum halide and paraflinic, naphthenic or even olefinic hydrocarbons inthe presence of. a promoter. such as hydrogen chloride or hydrogen bromide. formed during this isomerization reaction or in the previous alkylation reaction i`s a suitable catalyst for our process. The aluminum chloride or The complex the reaction zone in the form of a slurry, or as a suspension or solution in, for example, a por-A halide we canvemploy any compound which in the presence of the catalyst aiords a hydrogen halide, particularly hydrogen chloride or hydrogen bromide, under the reaction conditions, preferably in an amount suicient to supply a concentration in the reaction zone of about one t two mols of `hydrogen halide per 4mol of aluminum halide, which will usually be in the range of from about 0.03% to 3.0% by Weight'o'f hydrogen halide based on the charge. Our preferred promoter is hydrogen chloride but hydrogen bromide, carbon tetrachloride, alkyl halides such as methyl chloride, ethyl chloride, etc., or the corresponding bromine compounds, can be used.

The reactions are carried out under relatively. high total pressure, for example, from about 250 to about 3000 pounds per square inch and preferably about 500 to about 1500 pounds per square inch. 0f this total pressure, the partial pressure of hydrogen is from about 50 to 2500 pounds per square inch, preferably 400 to 1000 pounds per square inch. The hydrogen need not be a pure product but may contain such impurities as methane, ethane, etc., in which case thev total f pressure can be somewhat higher thanthat specifled above. The reaction can be carried out at temperatures ranging from about 100 F. to about 450 F., preferably about 250 to 350 F.

In our process it is quite possible to include butanes (including normal and/or isobutane) with the initial feed stock, in which case the isobutane present, if any, willbe converted to alkylated hydrocarbons in the alkylation reaction, and will therefore be Withdrawn either with the lower-boiling liquid-hydrocarbons by line 5| or with the higher boiling liquid hydrocarbonsin line 52, depending upon the olens used for alkylation. Unconverted butane will pass overhead from fractionator 39 through line 481 with the hydrogen, if any, and can be directed to isomerization reactor 54 Vfrom line 40 by opening valve 1| in line 12 which joins line 52. On the other hand,

we can introduce butane directly into the feed stream to reactor 54 by line I3 which joins line 12 leading to line 52. It is also possible to introduce fresh feed at this point and operate the re- -actor entirely on recycle stock from the fractionation of isomerized hydrocarbons. This in general produces a higher boiling product which is sometimes desirable.

Isomerizationreactor 54 can be maintained at the proper temperature by a jacket`14 through which ilows a heating medium from line `A'I5 which discharges through line-16. Other means for maintaining temperature within the reactor caribe' employed such as, for example, heating coils. induction heating, '-etc., such expediente bein well known to those skilled in the art. It

aluminum` bromide is preferably introduced into timat'e contact between the catalyst and the reactants be obtained which can be accomplished as illustrated by a stirrer 11 which provides violent agitaticn of the catalyst and reactants, or by such` other means as jet injectors, turbo-mixers,

packed towers, turbulent flow, etc.

y tion the catalyst can be discharged through line 82' by opening valve 8 3 for discard or for the recovery of aluminum halide. If, however, it is still active, it can be recycled to the isomerization reactor by opening valve 84 in line 85 and valve 86 in line 81 which joins line 39. When low temperature isomerization has been employed in isomerization reactor 54, the complex formed therein by the reaction of the aluminum halide and the parafhnic hydrocarbons is a very suitable catalyst for carrying out the alkylation reaction and therefore the complex can be directed through line 88 to line I8 where it can supplement or replace fresh catalyst.

The hydrocarbons together with the unreacted hydrogen and hydrogen halide pass from separator 19 to fractionator 88 by line 90.` Top cooling means 8|', bottom-heating means 92, which can be reilux and reboiler means or cooling and heating coils of any desired description, aid in the separation of the various products from separator 19. Hydrogen together with hydrogen halide, if present, pass overhead through line 93 and can be discarded by` opening valve 94 in line 95. However, it is usually desirable to recycle either or both ofthese to the .isomerization reaction by opening the valve in line 85 which joins line 18 or by recycling it to the alkylation reactor byl opening valve 91 in line 98 which joins line 24. It is possible to direct a part to the isomerization reaction and part to the Ais essential to the isomerlzation reaction that inalkylaticn reaction vby the proper' manipulation of valves 91 and 99. The isomerized hydrocarbons which comprise chieiiy isopentane and iso- Vhexane, together with isobutane if butanes were present, are withdrawn from fractionator 88 by line |05 and can be withdrawn from the system by opening valve |06 in line |01. However, we prefer .to employ the lsomerized hydrocarbons in our motor fuel. Accordingly. by opening valve |08 in line |09 we can direct them to line H0 by opening valve therein which` leads to blending tank 59 wherein they are blended with the higher-boiling alkylates from line 68. Alternately, we can return these to the alkylation reaction for the production of further quantities of higher-boiling hydrocarbons by opening valve H2 in line ||3 which joins line I0. It is also possible tn recycle a part of the isomerized hydrocarbons to the alkylation` reaction and to difractionator Il byopening valve |I4 in line H5.A

Although we have previously described the operation of the isomerization reaction as taking place in the low temperature range of from 10.0 F. to 450 F., our process can be carried out by gradually increasing the temperature from 100 F. to 450 F. or to some intermediate temperature less than 450 Rand higher than 100 F. In this case the catalyst, which becomes more and more spent as it isl recycled, can be utilized further. In this way we can` completely exhaust the catalytic activity of our catalyst as regards isomerization. Moreover, our catalyst can also be suitably utilized by withdrawing the catalyst from tion to certain preferred embodiments thereof, it should be understood that this is by way of illustration and not by way` of limitation, and that we are to be limited only insofar as is set forth in the appended claims.

We claim:

1. The method of preparing a charging stockv for an isomerization system which comprises alkylation as it becomes gradually spent iorfoptimum activity and directing it to isomerization reactor 54 by line 34, as previously described, and thereupon, starting with a low temperature, gradually increase the temperature until complete exhaustion of the catalyst has been obtained.

By our process, using for example a naphtha having a boiling range of from about 30 F. to 152 F. obtained from the fractionation of a straight-run naphtha from a Mid-Continent crude and having an octane number of about 67-68, we can obtain a motor-fuel of 80 to 90 octane number with a yield of 100 cent by volume based onv naphtha.

Although we have described our process as regards certainA apparatus, for the sake of clarity and simplicity certain details have been omitted; for example, top-cooling coils in any or all of the fractionating towers can be replaced by supplying reux to the towers froml an outside source or -by cooling and condensing the top products from the fractionator towers and returning a portion of them to act as reux. Similarly, in place -of the bottom-heating means in the fractionators,

we can withdraw a portion of the heavy product, heat it to increase the temperature sufficiently, and return the 'heated products to the fractionator whereby heat is supplied to the products to be fractionated'. Also, we have omitted certaindetails as regards pumps, heat exchangers, cooling means, pressure release valves, etc., all of which will occurreadily to one skilled in the art and which would naturally be used in any commercial plant employing our process.

In addition to increasing the octane number considerably, we also obtain a balanced fuel, comprising branched-chain hydrocarbons having from at least live to eight or nine carbon atoms per molecule. By our process, the boiling range is extended considerably over that found in the products from such processes as the polymeriza- .tion of butylenes, or the alkylation of isobutane with' butylenes, which are used for theiproduction of "isooctane, and the volatility characteristics of our product are therefore much superior. Moreover, such fuels have excellent lead response and high heat content-both desirable for aviation fuels. A

We have also converted a` comparatively low octane-number naphtha of too great volatility to a high octane number gasoline of suitable volatility by the production of branched-chain hydrocarbons from straight-chain paraflins, and by the alkylation of low-'boiling constituents to higherboiling constituents, thereby lowering the vapor pressure. In addition, we have provided a process in which the catalyst can be advantageously employed to give optimum yields per unit of catalyst used, and can be cycled from either process to the other under the conditions set-forth.

Although we have described our process in relato 120 pery fractionating alight paraflinic naphtha to remove .heptanes and heavier hydrocarbons from a (J5-Cs fraction containing both normal and isoparaiiinic hydrocarbons, alkylating said Cs-Cs fraction with said higher boiling point hydrocarbons from the unreacted normal para-filme Cs-Ca hydrocarbons whereby the concentration of normal paraiiin in the Cs-Cs fraction is increased by the removal of the isoparafiins therefrom by the final separation step which in turn is made possible by the alkylation step, and isomerizing said concentrated normal paraninic Cs-Ce hydrocarbons with said separated catalyst in the presence of hydrogen chloride and hydrogen whereby a greater amount of normal paraiilnic Cs-Ce hydrocarbons originally present in said light parailinic naphtha are converted to isoparaiilnic'Cs-Cs hydrocarbons than would otherwise be possible.

2. In the method of isomerizing normal paraffins in the presence of'an aluminum chloride catalyst to produce aviation gasoline constituents, the

improvement comprising contacting a hydrocarbon fraction comprising predominantly normal andisoparai'ilnic hydrocarbons having ve andsix carbon atoms per molecule with a normally gaseous olefin in the presence of an aluminum chloride catalyst vand hydrogen under conditions iins in the presence of an aluminum chloride catalyst to produce aviation gasoline constituents, the improvement comprising contacting a hydrocarbon fraction comprising predominantly normal and iso-parailinic hydrocarbons having live and six carbon atoms per molecule with a normally gaseous olen in the presence of an aluminum chloride catalyst under conditions adapted to promote the alkylation of at least a part of the isoparainic hydrocarbons with said oleiins, separating the alkylation product stream and the aluminum chloride catalyst, separating the unreacted hydrocarbons from the alkylation product stream to produce a residual fraction predominating in normal paraflinic hydrocarbon, isomerizing'the'residual normal parailinic fraction in the presence of aluminum chloride, catalyst separated from the alkylation product, separatingthe isomprisingisoparaiiinic hydrocarbons having ve and six carbon atoms per molecule, and utilizing in said first-mentioned contacting step at least a part of the aluminum chloride catalyst separated from 'said isomerization product stream.

4. A process for the production of motor fuel constituents which comprises the stepsof contacting a hydrocarbon fraction comprising essentially normal and iso-paraflinic hydrocarbons having ve and six carbon atoms per molecule with ethylene in the presence of an aluminum chloride catalyst under conditions adapted to promote the alkylation of at least a part of the said isoparamnic hydrocarbons with said ethylene,

separating the alkylation product stream and the aluminum chloride catalyst, separating from the alkylation product stream a fraction predominating in normal paraillns having five and six carbon atoms per molecule, contacting the last-mentioned fraction with an aluminum chloride catalyst and hydrogen halide under conditions adapted to convert at least a substantial part of said normal Aparaillns into branched chain hydrocarbons, separating the isomerization product stream and the aluminum chloride catalyst, and supplying separated aluminum chloride catalyst to said nnic hydrocarbons with said olefin, separating the,

alkylation product stream and the aluminum chloride catalyst, separating from the alkylation .product stream a. fraction predominating in normal paraiilns having ve and six carbon atoms per molecule, contacting the last mentioned fraction with an aluminum chloride catalyst and hydrogen halide under conditions adapted to convert at least a substantial part of said normal paratflns into branched-chain hydrocarbons, separating the conversion product stream and the aluminum chloride catalyst, and supplying separated aluminum chloride catalyst to said rst mentioned contacting step.

6. In the method of producing aviation gasoline constitutents by operations including alkylation and isomerization in the presence of an aluminum chloride catalyst, the improvement comprising contacting a hydrocarbon fraction comprising predominantly normal and isopar'afiinic hydrocarbons having five and six carbon atoms per molecule with an olefin in the presence of an aluminum chloride catalyst under conditions adapted to promote the alkylation of at least a. part of the isoparaflinic hydrocarbons with said olefin, separating the unreacted hydrocarbons from the alkylation product stream to produce a residual fraction predominating in normal parafiinic hydrocarbons, isomeriring the residual normal parafilnic fraction in the presence of an aluminum chloride catalyst, recovering separate bodies of an aluminum chloride catalyst from said alkylation and from said isomerization respectively, and supplying separated catalyst from at least one of said operations to the other.

BERNARD L. EVERING. EDMOND L. DOUVILLE. 

